1. Technical Field
This invention is directed to an aircraft icing detector which is critical in determining aircraft performance and safety. Ice accumulation on flight surfaces will often occur in conditions that would not seem likely. Modern aircraft design having more efficient wing characteristics make them more vulnerable to any ice accumulation that will decrease the lift efficiency and increase drag. If surface friction is increased by contamination and surface roughness which can be directly attributed to ice accumulation, increased drag will occur with flight performance and stabilization will be effected. Modern aircraft store fuel in the wings which will be chilled during flight thus creating lower flight surface temperatures which when combined with the ambient moisture content of the surrounding air can form ice even in non-freezing air conditions that would not normally be conducive to ice formation.
Clear ice formations on flight surfaces is especially dangerous since it cannot readily be seen by visual inspection and requires careful hands on inspection by properly trained personnel. Ice detection on aircraft's critical upper wing surface areas are difficult to inspect due to the wing height and wing dimension. Normal inspection procedures on such aircraft require a step ladder be positioned adjacent the wing allowing the inspection personnel to physically climb high enough so that a wide section of the wing area can be inspected by hand. Engine blade icing is also of a critical concern when ice forms on the fan blade surfaces found in modern jet and turbo-prop aircraft. Engine damage is caused by ice injection during take-off when ice breaks away from flight surfaces in front of the engine and is ingested impinging against the fan blades causing damage which can effect flight performance and engine output.
2. Objects and Advantages
It is the object of this invention to provide for a simple self-contained ice detection device that can be readily used by flight and ground personnel to easily and quickly inspect critical wing surfaces for the presence of ice especially clear ice which is less readily detectable by visual inspection.
An advantage of the invention is directed towards the absolute determination of ice presence by the relative conductivity of the wing surface allowing the flight and ground personnel to inspect the wing without physically touching it which heretofore is the most effective and most fail safe method of determining the accumulation of clear ice.
Description of Prior Art:
Prior art devices to help determine the presence of ice on flight surfaces before take-off have relied on both visual inspection and hands on inspection by flight and ground personnel, see for example U.S. Pat. Nos. 5,313,202, 5,180,122, 4,398,412, 3,045,223 and 2,432,669.
In U.S. Pat. No. 3,045,223 an ice detection device is disclosed that utilizes light transmission between a light source and detector to determine the presence of foreign material therebetween.
U.S. Pat. No. 4,398,412 is directed to a device to determine frost depth and density by using a hand held visual gauge through which the frost can be cited and thus measured.
U.S. Pat. No. 2,432,669 responds to the formation of ice by using the electrical capacitance principle in which one plate of the condenser is the pick-up dish mounted to an insulated plate on the wing. The other condenser plate is the wing itself thus measuring oscillating electrical fields between same as ice forms thereon.
U.S. Pat. No. 5,180,122 on an apparatus for de-icing illustrates apparatus and method for detecting ice on a flight surface by using a video camera to detect effect surface color differences which are processed to determine the presence of ice and the direction of a de-icing gun.
U.S. Pat. No. 5,313,202 relates to ice detection by determining the latant heat release as water freezes between two surfaces of a roter blade aircraft or the like.